Buggy code:
@ SuppressWarnings ( "serial" ) public class TransactionsTab extends JPanel implements ExportListener { private static final AppContext context = AppContext . instance ( ) ; private final DbDao dao = TransactionsTab . context . get ( DbDao . class ) ; private final MainFrame owner ; private final TransactionsTab . QueryPanel queryPanel ; private final TransactionsTab . FilterPanel filterPanel ; private final JPanel tablePanel ; private final TransactionsTab . StatsPanel statsPanel ; private ItemsTable itemsTable ; private MyJScrollPane itemsTableScrollPane ; private PlayersPanel playersPanel ; private TransactionsTable transactionsTable ; private MyJScrollPane transactionsTableScrollPane ; private int netTotal ; public TransactionsTab ( MainFrame owner ) { } private void filter ( FilterList items , FilterList players ) { } private void sort ( TransactionsTab . SortItem selected ) { } public void clear ( ) { } public void updateComplete ( boolean showResults , boolean firstUpdate ) { } public void showItems ( final DateRange range , final boolean shopTransactions ) { } public void showPlayers ( final DateRange range , final boolean shopTransactions ) { } private void showTransactions ( final DateRange range , final boolean shopTransactions ) { } private void updateNetTotal ( ) { } private void updateCustomers ( ) { } public void setShowQuantitiesInStacks ( boolean stacks ) { } @ Override public String exportData ( ExportType type ) { } private class QueryPanel extends JPanel { private final DateFormat dateFormat = DateFormat . getDateInstance ( DateFormat . MEDIUM ) ; private final DateFormat dateTimeFormat = DateFormat . getDateTimeInstance ( DateFormat . MEDIUM , DateFormat . SHORT ) ; private final JPanel fullPanel ; private final JRadioButton entireHistory ; private final JRadioButton showSinceLastUpdate ; private final JRadioButton dateRange ; private final JRadioButton shopTransactions ; private final JRadioButton myTransactions ; private final DatePicker fromDatePicker ; private final DatePicker toDatePicker ; private final JButton compress ; private final JButton showItems ; private final JButton showPlayers ; private final JButton showTransactions ; private final JPanel compressedPanel ; private final JButton expand ; private final JButton showItemsSmall ; private final JButton showPlayersSmall ; private final JButton showTransactionsSmall ; private final JLabel description ; private final List < TransactionsTab . SearchListener > listeners = new ArrayList < TransactionsTab . SearchListener > ( ) ; public QueryPanel ( ) { } public void reset ( ) { } public void addSearchListener ( TransactionsTab . SearchListener listener ) { } private void onSearch ( TransactionsTab . SearchType type ) { } private void setCompressed ( boolean compressed ) { } private boolean checkDateRange ( ) { } public DateRange getDateRange ( ) { } private void updateEntireHistoryCheckbox ( ) { } private void updateSinceLastUpdateCheckbox ( ) { } private void setDescription ( TransactionsTab . SearchType type , DateRange range ) { } } public class FilterPanel extends JPanel { private final JLabel filterByItemLabel ; private final FilterTextField filterByItem ; private final JLabel filterByPlayerLabel ; private final FilterTextField filterByPlayer ; private final JLabel sortByLabel ; private final TransactionsTab . SortComboBox sortBy ; private final ExportButton export ; private final List < TransactionsTab . FilterListener > filterListeners = new ArrayList < TransactionsTab . FilterListener > ( ) ; private final List < TransactionsTab . SortListener > sortListeners = new ArrayList < TransactionsTab . SortListener > ( ) ; public FilterPanel ( ExportListener listener ) { } public void setVisible ( boolean item , boolean player , boolean sort ) { } public void addFilterListener ( TransactionsTab . FilterListener listener ) { } public void addSortListener ( TransactionsTab . SortListener listener ) { } public void clear ( ) { } } private static class SortComboBox extends JComboBox { public SortComboBox ( ) { } @ Override public TransactionsTab . SortItem getSelectedItem ( ) { } } private static enum SortItem { PLAYER ( "Player<seq2seq4repair_space>Name" ) , HIGHEST ( "Highest<seq2seq4repair_space>Net<seq2seq4repair_space>Total" ) , LOWEST ( "Lowest<seq2seq4repair_space>Net<seq2seq4repair_space>Total" ) ; private final String display ; private SortItem ( String display ) { } @ Override public String toString ( ) { } } private static enum SearchType { ITEMS , PLAYERS , DATES ; } private interface SearchListener { void searchPerformed ( DateRange range , TransactionsTab . SearchType type , boolean shopTransactions ) { } } private interface FilterListener { void filterPerformed ( FilterList items , FilterList players ) { } } private interface SortListener { void sortPerformed ( TransactionsTab . SortItem sort ) { } } private class StatsPanel extends JPanel { private final JLabel netTotalLabel ; private final JLabel gainedLabel ; private final JLabel lostLabel ; private final JLabel customersLabel ; private final JLabel customers ; public StatsPanel ( ) { } public void setGained ( int gained ) { } public void setLost ( int lost ) { } public void setNetTotal ( int netTotal ) { } public void setCustomers ( Integer customers ) { } public void setShopsVisited ( Integer shopsVisited ) { <START_BUG> boolean show = ( customers ) != null ; <END_BUG> if ( show ) { customersLabel . setText ( "<html><font<seq2seq4repair_space>size=5>Shops<seq2seq4repair_space>Visited:" ) ; customers . setText ( ( "<html><font<seq2seq4repair_space>size=5><code>" + shopsVisited ) ) ; } customersLabel . setVisible ( show ) ; this . customers . setVisible ( show ) ; } } }

Fix:
boolean show = shopsVisited != null ;